Proceed With Caution: Pre- And Post-Characterising Claims Ahead

• Published date: 27 January 2022
• Subject Matter: Intellectual Property, Media, Telecoms, IT, Entertainment, Patent, Media & Entertainment Law
• Law Firm: Dehns
• Author: Mr Paul Harris

The life of a patent attorney is hard enough as it is, but using the EPO claim drafting convention, one would be forgiven for thinking that after carefully steering around the prior art in the 'pre-characterising' portion of the claim, that would be enough. Not so.

In the recent Court of Appeal decision of Lufthansa Technik AG v Astronics Advanced Electronics Systems and ors [2022] EWCA Civ 20 the distinction fell to be considered. In the judgement of LJ Birss, he said:

This case highlights a curiosity of the pre/post characterising approach to claim drafting. When drafted this way the characterising features of the claim explain what the patentee thought were features not disclosed in the prior art on which the pre-characterising part was based..... In other words these characterising features are presented as representing the inventive step over that prior art. However the challengers to validity in this case, as they are entitled to, rely on different prior art. In response the patentee seeks to identify distinctions over that other prior art. As it turns out in this case those distinctions are features of the pre-characterising part. So the inventive step (if it is one) over the other prior art may very well not be the features in the characterising portion of the claim at all. I mention this only to make the point that it is a legitimate approach for patentees to take. Many good inventions amount to new combinations of old features. The fact that each of the individual features making up a claimed invention can be found in various places in the prior art may well help the party challenging validity to make their case but it does not, on its own, prove that a claim lacks an inventive step.

The case concerned plug sockets in aircraft seats. The patent's invention lay in the socket detecting a plug's insertion, and that the power supply was 'remote' from the socket. The arguments revolved around whether there was a need for full insertion or only partial insertion, and what was understood by 'remote'. If the claim was construed (normally and...